JP7135787B2 - turbocharger - Google Patents

Description

The present invention relates to turbochargers.

A turbine wheel is housed in a turbine housing in the turbocharger of Patent Document 1. The turbine housing is partitioned with a bypass passage that bypasses the exhaust upstream side of the turbine wheel and the exhaust downstream side of the turbine wheel. A wastegate valve that opens and closes the bypass passage is attached to the turbine housing. A shaft of the wastegate valve is rotatably supported on the wall of the turbine housing. A support arm extends radially outwardly of the shaft from the end of the shaft. A valve body is supported by the support arm so as to be able to swing with respect to the support arm.

When the bypass passage is fully closed in the turbocharger of Patent Document 1, the shaft rotates to one side so that the valve element approaches the valve seat of the bypass passage. Then, the valve body swings along the valve seat, so that the valve seat and the valve body come into close contact with each other and the bypass passage is fully closed.

JP 2009-092026 A

In the turbocharger of Patent Literature 1, if the amount of tracing (swinging amount) of the valve disc with respect to the valve seat is not sufficient, there is a risk that a gap will occur between the valve seat and the valve disc when the bypass passage is fully closed. If there is an excessive gap between the valve seat and the valve body, an excessive amount of exhaust gas will be discharged from the bypass passage even though the wastegate valve is controlled so that the bypass passage is fully closed. It can leak out.

A turbocharger for solving the above-mentioned problems comprises a turbine housing that houses a turbine wheel and has a bypass passage that bypasses the exhaust upstream side and the exhaust downstream side of the turbine wheel; and a wastegate valve for opening and closing a bypass passage, wherein a valve seat for the wastegate valve is provided at an opening edge of the bypass passage on an inner wall surface of the turbine housing. At one of the seat and the wastegate valve, when the bypass passage is brought from the open state to the fully closed state, the other of the valve seat and the wastegate valve is contacted with the other one of the valve seat and the wastegate valve. There is provided a deformation portion that deforms according to the shape of the.

With the above configuration, even if the wastegate valve cannot swing so as to follow the valve seat, or if the amount of follow is small, the deformed portion will not deform when the bypass passage is fully closed. can ensure tight contact between the valve seat and the wastegate valve. Therefore, when the bypass passage is fully closed, the gap between the valve seat and the wastegate valve can be reduced.

In the above configuration, the deformable portion may be an abradable portion made of a material having a machinability index greater than that of the material forming the valve seat and the wastegate valve. In the above configuration, the abradable portion is ground to match the shape of the other of the valve seat and the wastegate valve in the process of repeatedly closing the bypass passage. That is, the abradable portion irreversibly deforms to match the shape of the other of the valve seat and the wastegate valve. Therefore, even if the other surface of the valve seat and the wastegate valve has some unevenness, the abradable portion can be ground according to the unevenness, so sufficient adhesion can be ensured between the two when the bypass passage is fully closed.

In the above configuration, the deformable portion is a disc spring having an annular spring portion, and the spring portion moves from one of the valve seat and the wastegate valve to the other when the bypass passage is fully closed. and curved radially inward of the spring portion.

In the above configuration, when the bypass passage is changed from the open state to the fully closed state, the spring portion of the disc spring is elastically deformed according to the shape of the other of the valve seat and the waste gate valve. Therefore, it is possible to ensure sufficient adhesion between the other of the valve seat and the waste gate valve and the disc spring without waiting for irreversible deformation of the disc spring.

In the above configuration, the waste gate valve opens and closes the downstream end of the bypass passage, the disc spring is fixed to the waste gate valve, and the spring portion is arranged radially inward of the spring portion. may be curved.

In the above configuration, when the bypass passage is in the fully closed state, the spring portion of the disc spring contacts the other of the valve seat and the wastegate valve. Then, the spring portion of the disc spring is bent radially inward and elastically deformed as if the spring portion were compressed in the central axis direction. On the other hand, since the waste gate valve opens and closes the downstream end of the bypass passage, the pressure inside the bypass passage becomes relatively high when the bypass passage is in a fully closed state. The pressure in the bypass passage pushes the spring portion of the disc spring radially outward, so that the spring portion bends radially outward and the amount of compression of the spring portion in the direction of the central axis decreases. That is, in the above configuration, excessive elastic deformation of the spring portion of the disc spring in the direction of the central axis can be suppressed, and so-called settling is less likely to occur in the spring portion.

1 is a schematic diagram of an internal combustion engine in a first embodiment; FIG. Sectional drawing of the turbocharger in 1st Embodiment. FIG. 2 is a cross-sectional view of the turbocharger showing the peripheral configuration of the wastegate valve in the first embodiment; Sectional drawing of the turbocharger which shows the peripheral structure of the wastegate valve in 2nd Embodiment.

<First embodiment>
The first embodiment will be described below with reference to FIGS. 1 to 3. FIG. First, a schematic configuration of an internal combustion engine 100 of a vehicle will be described.

As shown in FIG. 1, the internal combustion engine 100 includes an intake passage 11 through which intake air from the outside of the internal combustion engine 100 flows. The intake passage 11 is connected to a cylinder 12 that mixes and burns fuel with intake air. An exhaust passage 13 for discharging exhaust gas from the cylinder 12 is connected to the cylinder 12 .

The internal combustion engine 100 includes a turbocharger 20 for compressing intake air using exhaust flow. A compressor housing 21 of the turbocharger 20 is attached to the intake passage 11 . A turbine housing 30 of the turbocharger 20 is attached to the exhaust passage 13 . Compressor housing 21 and turbine housing 30 are connected via bearing housing 22 in turbocharger 20 .

A turbine wheel 78 that is rotated by the flow of exhaust gas is housed inside the turbine housing 30 . One end of a connecting shaft 77 is connected to the turbine wheel 78 . An axial center portion of the connecting shaft 77 is housed inside the bearing housing 22 . The connecting shaft 77 is rotatably supported by bearings (not shown) inside the bearing housing 22 . A compressor wheel 76 is connected to the other end of the connecting shaft 77 . The compressor wheel 76 is housed inside the compressor housing 21 .

Next, the turbine housing 30 in the turbocharger 20 and its related configuration will be specifically described.
As shown in FIG. 2, the turbine housing 30 is defined with a scroll passage 31 for introducing exhaust from the outside. The scroll passage 31 extends in the circumferential direction around the rotation axis of the turbine wheel 78 (the rotation axis of the connecting shaft 77) so as to surround the turbine wheel 78. As shown in FIG. An upstream end of the scroll passage 31 is connected to the exhaust passage 13 upstream of the turbine housing 30 .

The turbine housing 30 defines a substantially cylindrical housing space 32 in which the turbine wheel 78 is housed. The accommodation space 32 is connected to the downstream end of the scroll passage 31 . A discharge passage 33 for discharging the exhaust to the outside is defined in the turbine housing 30 . The discharge passage 33 is connected to the accommodation space 32 and extends generally in the rotational axis direction of the turbine wheel 78 . A downstream end of the exhaust passage 33 is connected to the exhaust passage 13 downstream of the turbine housing 30 .

The exhaust that has passed through the scroll passage 31 in the turbine housing 30 and blown against the turbine wheel 78 is discharged to the exhaust passage 13 on the downstream side of the turbine housing 30 through the exhaust passage 33 in the turbine housing 30 . At this time, the exhaust that has passed through the scroll passage 31 is blown against the turbine wheel 78, causing the turbine wheel 78 to rotate. When the turbine wheel 78 rotates, the compressor wheel 76 rotates via the connecting shaft 77 to supercharge the intake air.

A bypass passage 34 that connects the scroll passage 31 and the discharge passage 33 is defined in the turbine housing 30 . That is, the bypass passage 34 bypasses the exhaust upstream side and the exhaust downstream side of the turbine wheel 78 . The bypass passage 34 is a hole having a substantially circular cross-sectional view that penetrates the wall portion that separates the scroll passage 31 and the discharge passage 33 . A portion of the inner wall surface of the turbine housing 30 that includes the downstream opening edge of the bypass passage 34 functions as a valve seat 36 . The surface of the valve seat 36 is flush.

In this embodiment, the material of the turbine housing 30 is heat-resistant cast steel, and the heat-resistant cast steel has a machinability index of about 20 to 50, for example. Here, the machinability index is a value that indicates the machinability of a material relative to sulfur free-cutting steel, and a material with a higher machinability index is more likely to be cut.

As shown in FIG. 2 , a wastegate valve 40 that opens and closes the downstream end of the bypass passage 34 is arranged in the discharge passage 33 in the turbine housing 30 . A shaft 41 in the wastegate valve 40 has a substantially circular rod shape. The shaft 41 penetrates the wall of the turbine housing 30 and partially extends to the outside of the turbine housing 30 . The shaft 41 is rotatably supported by the wall of the turbine housing 30 .

As shown in FIG. 2 , a link mechanism 50 is connected to the end of the shaft 41 on the outside of the turbine housing 30 . As shown in FIG. 1 , an actuator 60 (for example, an electric motor) is connected to the link mechanism 50 as a drive source for controlling the opening and closing of the wastegate valve 40 .

As shown in FIG. 3 , a substantially columnar connecting portion 42 extends radially outward of the shaft 41 from an end portion of the shaft 41 on the inner side of the turbine housing 30 . A substantially disk-shaped valve body 43 is fixed to the end of the connecting portion 42 . In this embodiment, the wastegate valve 40 is configured by integrally molding the shaft 41, the connecting portion 42, and the valve body 43. As shown in FIG. The outer diameter of the valve body 43 is larger than the inner diameter of the valve seat 36 (the diameter of the downstream opening of the bypass passage 34). The material of the entire wastegate valve 40 including the shaft 41, the connecting portion 42, and the valve body 43 is heat-resistant steel, and the heat-resistant steel has a machinability index of about 20 to 50, for example.

An abradable portion 80 as a deformable portion is fixed to the facing surface 43 a of the valve body 43 . The abradable portion 80 extends along the outer edge of the facing surface 43a of the valve body 43 and has an annular shape as a whole. The outer diameter of the abradable portion 80 is approximately the same as the outer diameter of the valve body 43 . Also, the inner diameter of the abradable portion 80 is substantially the same as the inner diameter of the valve seat 36 . The material of the abradable portion 80 is a nickel-aluminum alloy or the like, and the machinability index of the nickel-aluminum alloy is about 180 to 300, for example. Moreover, the abradable portion 80 is formed by thermal spraying, and is configured to have pores inside. Therefore, the machinability index of the abradable portion 80 is greater than the machinability index of the valve seat 36 in the turbine housing 30 and the machinability index of the valve body 43 of the wastegate valve 40 . 2 and 3, the thickness of the abradable portion 80 in the central axis direction is exaggerated and enlarged.

The action and effect of this embodiment will be described.
As shown in FIG. 3, when the bypass passage 34 is changed from the open state to the fully closed state, the actuator 60 is driven to rotate the shaft 41 to one side in the circumferential direction (clockwise in FIG. 3). move. Then, the valve body 43 rotates to one side in the circumferential direction together with the shaft 41 , and the valve body 43 approaches the valve seat 36 . Here, in this embodiment, the valve body 43 is integrated with the shaft 41 and cannot swing with respect to the shaft 41 . Therefore, even if the abradable portion 80 fixed to the valve body 43 is designed to be in close contact with the valve seat 36 when the wastegate valve 40 is fully closed, manufacturing errors in the wastegate valve 40 and the valve seat 36 may occur. As a result, the abradable portion 80 may not come into close contact with the valve seat 36, resulting in a gap between them.

Specifically, for example, the distance between the shaft 41 of the wastegate valve 40 and the valve seat 36 may be smaller than the designed distance. In this case, the portion of the abrable portion 80 that is closer to the shaft 41 (the upper portion in FIG. 3) contacts the valve seat 36, while the portion of the abrable portion 80 that is farther from the shaft 41 (the upper portion in FIG. 3) is in contact with the valve seat 36. lower portion) does not abut against the valve seat 36. Therefore, a gap is generated between the valve body 43 and the valve seat 36 even though the wastegate valve 40 is controlled so that the bypass passage 34 is fully closed.

In the present embodiment, the machinability index of the abradable portion 80 is large, and the abradable portion 80 is easily abraded by coming into contact with the valve seat 36 . Therefore, as in the above example, when part of the abradable portion 80 abuts the valve seat 36 when the bypass passage 34 is changed from the open state to the fully closed state, the bypass passage 34 is repeatedly brought into the fully closed state. , the portion of the abradable portion 80 that contacts the valve seat 36 is gradually shaved, while the portion that does not contact is not shaved. Therefore, the abradable portion 80 is gradually cut to match the shape of the valve seat 36 . As a result, even if there is a gap between the abradable portion 80 and the valve seat 36 when the abradable portion 80 is not ground, the gap between the abradable portion 80 and the valve seat 36 is gradually reduced. As a result, tight contact between the abradable portion 80 and the valve seat 36 can be ensured when the bypass passage 34 is fully closed.

By the way, in the fully closed state of the bypass passage 34, in order to suppress leakage of the exhaust gas in the bypass passage 34 to the discharge passage 33, the surface pressure between the abradable portion 80 and the valve seat 36 should be equal to or higher than a predetermined value. It is necessary that Therefore, for example, if the surface of the valve seat 36 is uneven or distorted, the surface pressure of a part of the region where the abradable portion 80 and the valve seat 36 are in contact becomes less than a predetermined value, causing exhaust in the bypass passage 34 to be exhausted. may leak into the discharge passage 33.

In this embodiment, even if the surface of the valve seat 36 is not completely flat and has some unevenness or distortion, the shape of the abradable portion 80 changes according to the shape of the valve seat 36 by grinding the abradable portion 80 . do. Therefore, the surface pressure between the abradable portion 80 and the valve seat 36 is made uniform over the entire region where they are in contact with each other. By equalizing the surface pressure between the two in this way, it is possible to prevent the exhaust gas in the bypass passage 34 from leaking into the discharge passage 33 due to the surface pressure becoming excessively low.

<Second embodiment>
A second embodiment will be described below with reference to FIG. In the following description of the second embodiment, the differences from the first embodiment will be mainly described, and the same reference numerals will be given to the same configurations as in the first embodiment, and detailed description will be omitted. Or simplify.

As shown in FIG. 4 , a disc spring 90 as a deformation portion is fixed to the valve body 43 . An annular portion 92 of the disc spring 90 extends to surround the outer peripheral surface of the valve body 43 and has an annular shape as a whole. The inner diameter of the annular portion 92 is approximately the same as the outer diameter of the valve body 43 . A fixing portion 93 protrudes radially inward of the annular portion 92 from the end portion of the annular portion 92 on the back surface 43 b side of the valve body 43 . The fixed portion 93 extends along the outer edge of the back surface 43b of the valve body 43 and has an annular shape as a whole. The annular portion 92 and the fixed portion 93 are fixed to the valve body 43 by welding. A spring portion 91 protrudes in the central axis direction of the annular portion 92 from the end portion of the annular portion 92 on the side of the facing surface 43 a of the valve body 43 . That is, the spring portion 91 protrudes from the valve element 43 side toward the valve seat 36 side when the bypass passage 34 is fully closed. Further, the spring portion 91 is curved toward the inner side in the radial direction of the annular portion 92 as it protrudes toward the distal end side. The spring portion 91 is elastically deformable in the central axis direction of the spring portion 91 . The spring portion 91 is provided over the entire circumferential direction of the annular portion 92 and has an annular shape as a whole.

The action and effect of this embodiment will be described.
As shown in FIG. 4, when the bypass passage 34 is changed from the open state to the fully closed state, the actuator 60 is driven to rotate the shaft 41 to one side in the circumferential direction (clockwise in FIG. 4). move. Then, the valve body 43 rotates to one side in the circumferential direction together with the shaft 41 , and the valve body 43 approaches the valve seat 36 .

Here, for example, it is assumed that the portion of the spring portion 91 near the shaft 41 (the upper portion in FIG. 4) comes into contact with the valve seat 36 first. Then, the portion of the spring portion 91 close to the shaft 41 is elastically deformed so as to be compressed in the central axis direction of the spring portion 91 . When the shaft 41 further rotates, the portion of the spring portion 91 near the shaft 41 is strongly pressed against the valve seat 36 and elastically deformed greatly. On the other hand, the portion of the spring portion 91 away from the shaft 41 (the lower portion in FIG. 4) contacts the valve seat 36, but the pressing force against the valve seat 36 is not large, so the amount of elastic deformation is small. small.

Thus, even if there is a difference in the distance between the valve body 43 and the valve seat 36 between the side closer to the shaft 41 and the side farther from the shaft 41 when the bypass passage 34 is fully closed, the difference in distance is It can be offset by the difference in the amount of elastic deformation. Therefore, the tight contact between the spring portion 91 and the valve seat 36 can be ensured when the bypass passage 34 is fully closed.

Further, the spring portion 91 of the disc spring 90 is elastically deformed according to the shape of the valve seat 36 when the bypass passage 34 is changed from the open state to the fully closed state. Therefore, for example, unlike the abradable portion 80 in the first embodiment, there is no need to wait for irreversible deformation of the disc spring 90 caused by repeatedly bringing the bypass passage 34 into the fully closed state. 36 can be secured quickly.

By the way, when the bypass passage 34 is in the fully closed state, the spring portion 91 of the disc spring 90 abuts against the valve seat 36, so that the spring portion 91 bends radially inwardly of the spring portion 91. . At this time, the spring portion 91 is elastically deformed as if it were compressed in the central axis direction of the spring portion 91 . On the other hand, the wastegate valve 40 opens and closes the downstream end of the bypass passage 34 . Therefore, when the bypass passage 34 is fully closed, the pressure inside the bypass passage 34 is relatively high. Then, the pressure in the bypass passage 34 acts on the disc spring 90 , so that the spring portion 91 of the disc spring 90 is pushed radially outward of the spring portion 91 . Then, the amount of compression of the spring portion 91 in the direction of the center axis becomes small. As a result, in the present embodiment, the amount of elastic deformation of the spring portion 91 of the disc spring 90 in the direction of the center axis is smaller than when the pressure in the bypass passage 34 does not act on the disc spring 90 . As a result, it is possible to prevent the spring portion 91 of the disc spring 90 from being unable to return to its original state due to excessive elastic deformation.

This embodiment can be implemented with the following modifications. This embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
- In the first embodiment, the shape of the abradable portion 80 can be changed as long as it can contact at least the entire opening edge of the bypass passage 34 on the downstream side (the opening edge of the valve seat 36). For example, the abradable portion 80 may have a disc shape that covers the entire facing surface 43 a of the valve body 43 .

- In the above-described first embodiment, the materials of the turbine housing 30, the waste gate valve 40, and the abradable portion 80 are examples, and can be changed as appropriate. No matter what materials the turbine housing 30 (valve seat 36) and the waste gate valve 40 (valve element 43) are made of, the material of the abradable portion 80 is a material with a higher machinability index than these materials. For example, the presence of the abradable portion 80 can suppress leakage of exhaust gas when the bypass passage 34 is fully closed.

- In the said 1st Embodiment, the fixed object of the abradable part 80 can be changed. Specifically, the abradable portion 80 may be fixed to the valve seat 36 instead of the valve body 43 . Also, the abradable portion 80 may be fixed to both the valve body 43 and the valve seat 36 .

- In the second embodiment, instead of the valve body 43, a disc spring 90 may be fixed to the valve seat .
- In the said 2nd Embodiment, the shape of the disc spring 90 can be changed. For example, when the spring portion 91 of the disc spring 90 is fixed to the facing surface 43a of the valve body 43 by welding or the like, the annular portion 92 and the fixing portion 93 may be omitted.

In addition, for example, when the spring portion 91 of the disc spring 90 is unlikely to become sag, the spring portion 91 is curved radially outward of the annular portion 92 as it protrudes toward the distal end side. good too. Specifically, when the spring portion 91 is fixed to the central portion of the facing surface 43 a of the valve body 43 , the spring portion 91 contacts the valve seat 36 even if the spring portion 91 is curved radially outward. can contact In order to suppress the settling of the spring portion 91 of the disc spring 90, the amount of elastic deformation of the spring portion 91 can be reduced by reducing the amount of rotation of the valve body 43 that is rotated by driving the actuator 60. .

- In the first and second embodiments, the waste gate valve 40 may open and close the upstream end of the bypass passage 34 .

DESCRIPTION OF SYMBOLS 11... Intake passage 12... Cylinder 13... Exhaust passage 20... Turbocharger 21... Compressor housing 22... Bearing housing 30... Turbine housing 31... Scroll passage 32... Accommodating space 33... Exhaust passage 34 Bypass passage 36 Valve seat 40 Waste gate valve 41 Shaft 42 Connection portion 43 Valve body 43 a Opposing surface 43 b Rear surface 50 Link mechanism 60 Actuator 76 Compressor Wheel 77 Connecting shaft 78 Turbine wheel 80 Abradable portion 90 Belleville spring 91 Spring portion 92 Annular portion 93 Fixed portion 100 Internal combustion engine.

Claims (3)

a turbine housing containing a turbine wheel and having a bypass passage that bypasses the exhaust upstream side and the exhaust downstream side of the turbine wheel;
a wastegate valve that is attached to the turbine housing and opens and closes the bypass passage, the turbocharger comprising:
A valve seat for the wastegate valve is provided at an opening edge of the bypass passage on the inner wall surface of the turbine housing,
When one of the valve seat and the wastegate valve is in the fully closed state from the open state of the bypass passage, the valve seat and the wastegate valve are in contact with the other of the valve seat and the wastegate valve. is provided with a deformation part that deforms according to the shape of the other ,
The deformable portion is an abradable portion made of a material having a machinability index greater than that of the material forming the valve seat and the wastegate valve,
The material of the abradable portion is a nickel-aluminum alloy
A turbocharger characterized by: a turbine housing containing a turbine wheel and having a bypass passage that bypasses the exhaust upstream side and the exhaust downstream side of the turbine wheel;
a wastegate valve that is attached to the turbine housing and opens and closes the bypass passage, the turbocharger comprising:
A valve seat for the wastegate valve is provided at an opening edge of the bypass passage on the inner wall surface of the turbine housing,
When one of the valve seat and the wastegate valve is in the fully closed state from the open state of the bypass passage, the valve seat and the wastegate valve are in contact with the other of the valve seat and the wastegate valve. is provided with a deformation part that deforms according to the shape of the other,
The deformable portion is an abradable portion made of a material having a machinability index greater than that of the material forming the valve seat and the wastegate valve ,
The abradable portion is configured to have pores inside.
A turbocharger characterized by: a turbine housing containing a turbine wheel and having a bypass passage that bypasses the exhaust upstream side and the exhaust downstream side of the turbine wheel;
a wastegate valve that is attached to the turbine housing and opens and closes the bypass passage, the turbocharger comprising:
A valve seat for the wastegate valve is provided at an opening edge of the bypass passage on the inner wall surface of the turbine housing,
The waste gate valve opens and closes the downstream end of the bypass passage,
A deformable portion is fixed to the wastegate valve that contacts the valve seat and deforms according to the shape of the valve seat when the bypass passage is changed from an open state to a fully closed state,
The deformation portion is a disc spring having an annular spring portion,
The spring portion protrudes from the wastegate valve toward the valve seat and curves radially inward of the spring portion when the bypass passage is fully closed.
A turbocharger characterized by:

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